Device for determining primer bead size in flash lamps



Sept. 15, 1 959 R.M.ANDERSON DEVICE FOR DETERMINING PRIMER BEAD SIZE IN FLASH LAMPS Filed Aug. 27. 1956 RObEBT' L' M. An

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DEVICE FOR DETERMINING PRIlVIER BEAD SIZE 1N FLASH LAlVIPS Robert M. Anderson, Euclid, Ohio, assignor to General Electric Company, a corporation of New York Application August 27, 1956, Serial No. 606,347 4 Claims. (Cl. 3 2420) in wires extending into said bulb in substantially sideby-side relation, a filament mounted across theinner ends of said pair of lead-in wires, primer beads on the inner tips of said lead-in Wires, a quantity of combustible material, for example shredded aluminum foil, loosely disposed throughout said bulb, and'an oxygen or other combustion supporting gas atmosphere. The fulminating material that forms the primer beads is comprised, for example, of finely divided zirconium metal powder, sodium chlorate powder and potassium perchlorate powder held together with a suitable binder such as nitrocellulose. The fulminatingmaterial or primer is ignited upon passing a current through the ignition filament. The primer in turn ignites the combustible material loosely disposed within the bulb which produces the actinic light for photographic purposes.

The time lapse from energizing of the ignition filament to maximum intensity of actinic light output is referred to as the time-to-peakcharacteristic of the lamp. The amount of primer or fulminating material contained in the primer beads of a flash lamp controls the time increacteristic of the lamp in order to efficiently utilize the actinic light generated. I 1 v I The primer beads are applied 'to'the' inner' lead-in wire tips between which an ignition filament has been fastened, for example, by dipping the tips of the lead-in wires, secured in a mount structure, into a suspension of the fulminating material having'a suitable viscosity such that the proper amount of material adheres upon withdrawal of the lead-in Wire tips. y

The mount structure referred to generally comprises a glass stern press through which the lead-in wires are sealed having a flare section thereon for sealing the mount into the bulb, lead-in wires extending through'said stem press and an ignition filament fastened between'the' inner extremities of said lead-in wires. To assure that the time-to-peak characteristics of the finished lamp fall within the predetermined limits, it is necessary during manufacture to periodically determine the amount of primer aflixed to the primered mount. This determination is presently made by means of an instrument-called a balopticon which is an optical device rer measurin converges the light from the source and its reflector'bnt'o the primer beads. A mirror reflects the magnified'microscope image to a large frosted glass screen. The frosted 2,904,746 -Pa tented Sept. 15, 1959 screen has a movable indicator attached to a micrometer dial. This optical system is mounted in a lighttight, closable booth which the operator enters to measure :1 given primer mount. The measurement is made by traversing the movable indicator across the projected image of the primer bead on the frosted glass screen and reading the micrometer dial.

This device is necessarily bulky and, due to the optical system. involved, .quite expensive, making it diflicult from an economic standpoint as Well as space limitation to. locate many balopticons throughout a manufacturing floor. As a result, the instrument is not handy to the machine operators and periodic testing is not consistently carried out. -In addition, the device is slow and in accurate since primer beads are irregularly shaped and variance in primer head length is not taken into consideration by the device. Reproducibility of results between different. operators is. very poor. While the balopticon appears to provide'a non-destructive type test, it is necessary nevertheless to discard the measured mount structure rather than return it to the machine for insertion in a lamp bulb due to its prolonged exposure to the atmosphere and handling by the operator. 1 I i It. is therefore one object'of my invention to providera small,' inexpensive device; for measuring primer bead size' suitable forfconvenient location at several positions throughout a manufacturingfl'oor.

It is another object of my invention to provide a device for rapid and accurate determination of primer bead-size by measuring the light generated upon flashing of a primered mount structure.

'' Still another object is to provide a device for measuring primer bead size in the operation of which operator error is substantially eliminated.

Briefly stated, in accordance With one aspect of my invention, I, provide a double compartmented light-tight chamber, in which one of said compartments is adapted for the insertion and flashing of a primered mount and the other compartment contains an energy-converting device for-translating light energy to electrical energy.

A, partition is provided between the compartments of said chamber having an orifice therein and a voltage meter is connected to the output of the energy-converting means for recording the electrical energy generated .by the flashing of the primer beads. Y I

Fig. .l' is an elevation of a primered mount structure.

Fig.;;2.fiisan elevation of a foil-filled photoflash lamp. Fig. 3-is-a schematic diagram showing the circuit for operation of the energy-conversion means and the voltage'me'ter for indication of the. energy generated upon flashing a primered mount.

' Fig. 4 is an isometric view, partly in section, of the primer bead measuring device of my invention.

Referri'ng- 'to the drawingfFig. 1 shows'a primer'ed mount as used iri the deviceof my invention. mount comprisesa glass sternpress '1 having a flared portion 2 'ithereo'n for sealing 'themountintothe neck end of the ,lamp-bulb and an exhaust tube 3 attached thereto through which the. flash lamp is evacuatedand filled with the desired amount of oxygen. .Sealed through the stem' pres's 1 is. a pair otlead-in wires 4 and '5 with an ignitionfilafilament '6.- ,Fig; 2 shows a complete foil-filled photoflash lampa'co'mprising a bulb 9, containing a quantity of readily combustibleshredded foil 14' or other filamentary maiteriali'avmountm asshown inI-Fig. 1 the. flare 2 of which: has -been-sea1edto the neck end of bulb. 9; a base r1 1 eemented-lto the neck endof said bulb. 9; with; the. outer ends of lead-in wires 4, 5 of said mount structure fas- 3 tened to the center contact 12 and the base shell contact 13 of the base 11.

Fig. 3 is a wiring diagram showing a source of DC. voltage v15 connected through a limiting resistor '16 and a switch i17 to the energy-converting device 18 with a voltage indicating device 19 connected to the output terminal of the energy-converting means '18 and a capacitor 20 connected in parallel with said voltage indicating device.

Fig. 4 shows one arrangement of the device of my invention comprising a base 21 upon which is mounted a light-tight double compartmented chamber 22 said chamber having a closable door 23 at one end thereof. In this embodiment, the door 23 is mounted by means of a hinge 24 fastened to one side of said door. Adjacent the closable door 23 in the compartment is fixed a mount holding bracket 25 comprising a non-conductive block having positioned therein female-type electrical contacts 26 and 27 positioned to receive the outer ends of the leadin wires of a mount placed in said holder and further containing a receptacle adapted to receive the exhaust tube of a mount positioned in the holder. The contacts 26 and 27 are connected to a source of direct current potential 28 of sufiicient energy to flash the primer beads of a mount placed in the mount holder when the switch 29 connected between the contact 26 of the mount holder and the source of potential 28 is closed. A partition 30 divides the light-tight chamber into two approximately equal compartments. The partition 30 may be of lighttransmitting and difiusing material, such as ground glass, or contain an orifice 31 axially aligned between the primer beads on the primered mount in one compartment and the energy-converting means in the other compartment. In the compartment at the opposite end of the chamber from the mount holding means and separated therefrom by the partition 30 is placed an energy-converting device 33 which is connected to a voltage meter 32 located outside the double compartmented chamber and mounted on the base 21. The energy-converting means 33 is connected to the meter 32 and to a suitable source of operating voltage as shown in Fig. 3.

A specific description of an embodiment of my invention suitable for determining the amount of primer in the primer beads of a mount structure for a No. flash lamp having a time-to-peak of 20 milliseconds is as follows. Two small chambers or compartments, each of about 5 inches wide, four inches long and six inches high, for example, metal utility cabinets, are connected together with a common wall or partition 30 in which there is a inch orifice 31 covered by a frosted difiusing glass. The chamber in which a mount is to be flashed has a closable door 23 upon which a bracket or mount holder 25 is mounted. The mount holder 25 contains the electrical terminals 26 and 27 to which the outer leads of the primer mounts are attached and is also located to position the mount so that the primer lead tips 7 and 8 are always a definite distance from the center of the orifice when the door 23 is closed. The source of D.C. potential 28 for flashing the primer mounts is two No. 6 dry cells in series (3 volts D.C.).

In the opposite end of the double compartmented chamber from the mount holder is located a capacitor 20 and a photoelectric cell 33. The photoelectric cell 33 is a GL1P39 phototube located so that the cathode of the tube is in direct line with the orifice 31 in the partition wall 30 between the compartments. The height of the cathode of the photocell and the diameter of the orifice are approximately equal. The GL1P39 phototube is used because of its response characteristics in the visible light range. The light response curve of anode current (microamps) versus anode voltage (volts) is practically flat in the 50-250 anode voltage range for this type phototube. Within the compartment containing the phototube is located a 1.0 microfarad, pyranol filled, low leakage capacitor 20 connected in series with the phototube 33. A one microfarad capacitor is selected so that a reasonable upscale reading on the voltage indicator could be obtained when a No. 5 primered mount is flashed. When primered mounts of a different size for lamps other than No. 5 are to be tested, the capacitor size to give a reasonable scale reading on the voltage indicator can easily be determined by test. Outside of the compartment in which the phototube and capacitor are located there are two A-3O Burgess batteries 15 in series volts D.C.). These batteries provide the operating voltage required for the phototube 33 and are connected in series with a limiting resistor 16 and a switch "17 to the phototube and capacitor.

In order to measure the voltage impressed across the capacitor 20 when a primered mount is flashed, a high impedance electrometer 32 (Kiethley Model No. 200) is used in order to prevent the capacitor from discharging. With the capacitor prevented from discharging, the

electrometer needle will hold the reading until the capacitor is manually discharged by means of a switch (not shown) which shorts the capacitor to ground and allows the indicator to return to zero scale position. This switch is operated by a push button 35 on the electrometer case. The electrometer 32 is connected to the chamber in which the phototube and capacitor are located by means of a metal flange 34. This flange serves as a ground connection to the electrometer and also shields the connecting wire between the phototube and the electrometer from external electrostatic charges. The positive side of the capacitor is connected to the electrometer by means of a banana plug which is kept an equal distance from the walls of the metal flange 34 by means of a Lucite disc.

In order to use the device to test mounts during highspeed production manufacture, it is necessary to calibrate the meter so that the tester will have some indication whether a given mount flashed falls within acceptable tolerances. This calibration may be effected by weighing out the exact amount of primer which is calculated to produce the desired time-to-peak characteristic in the finished flash lamp. This primer may then be applied to the inner ends of the lead-in wires of a mount structure. Upon flashing of the mount in the device of my invention, the electrometer needle will reach and hold a certain reading on the scale. Allowable variations in meter readings which will fall within acceptable manufacturing tolerances may then be marked on either side of the needle position. Thus, on flashing of production run mounts, the meter needle should stop within these two lines placed on the scale if the primer beads are within the manufacturing tolerances. An alternative way of calibrating the meter would be to prepare two primered mounts one containing the maximum allowable amounts of primer and the other the minimum amount to fall within manufacturing tolerance on the time-to-peak characteristic. Flashing of both of these mounts would then establish on the meter scale the upper and lower limits within which the needle must fall on subsequent mount testing.

With the meter thus calibrated to show the rangeof acceptable readings, the device may be placed on the manufacturing floor. In order to effectively control primer bead size it has been determined that a mount should be tested during each 15 minutes of a production run. To operate the device for primer bead testing it is necessary to close switch 17 which applies operating voltage to the photocell 33. A primered mount is then placed in the mount holder 25 and the door 23 closed. Closing switch 29 will flash the primer bead on the mount structure. The light emitted by this flash passes through the orifice 31 striking the phototube 33 which in turn impresses a voltage across the capacitor 20. Since the volt meter or electrometer 19 is connected in parallel with the capacitor 20, the same voltage will be recorded on'the meter dial. As previously pointed out, the high impedance electrometer will prevent the discharging of the capacitor so that the meter needle will hold the reading produced. If the meter needle falls within the calibration marks on the dial, the operator knows that the run is maintaining acceptable primer head size. During subsequent tests should the needle approach the up per limit, the operator is warned that the primer suspension in which the inner ends of the leads of the mount lead Wire are dipped is becoming too viscous and more solvent must be added to the suspension. Conversely, if the needle begins to approach the lower limit, the operator is warned that the primer suspension is too thin or of too low viscosity and not enough primer is adhering to the lead wires as they are dipped in the suspension. To correct this the operator may apply forced draft ventilation to evaporate excessive solvents and increase the viscosity of the primer suspension.

The device of my invention is of considerably lower cost than prior art devices for determining primer bead size. For example, the device costs about one-fifth as much as a balopticon currently used to make this determination. The lower cost also makes it feasible to locate more devices throughout the manufacturing floor. This places the devices closer to the production operators and facilitates routine and periodic checking as is required. It will also be appreciated that the device of my invention will provide the desired indication with much greater rapidity than the previous micrometer dial, optical system. Further, operator error is substantially reduced in using my device inasmuch as the determination does not in any way depend upon the party performing the test as would an optical device wherein irregular primer beads are measured by means of the eye. Reproducibility of results will not be affected by changes in operators performing the test.

The phototube operating voltage supplied by the batteries 15 may also be supplied by a rectifier and an alternating current source should it be desirable to eliminate the batteries from the device. The partition 30 between the two chambers of my device may be an opaque wall containing an orifice, as shown, covered by a frosted glass diffusing plate, or the entire partition may be formed of frosted glass as desired.

Although a preferred embodiment of my invention has been disclosed, it is recognized that variations and changes may be made therein within the spirit and scope of the invetnion as defined by the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A device for determining the primer bead size of foil-filled flash lamps comprising a double compartmented light-tight chamber, means for holding a primered mount in one of the compartments of said chamber, a pair of electrical contacts on said mount-holding means connected to a source of direct current voltage and adapted to contact the lead wires of a primered mount placed in said holding means, a switch connected between said source of direct current voltage and one of said pairs of electrical contacts, a light-diffusing partition between the compartments of said chamber, means for converting light to electrical energy in the other compartment of said chamber, a source of operating voltage connected in series with the negative terminal of said energy-converting means, a capacitor connected in series with the positive terminal of said energy-converting means, and a voltage meter connected in parallel with said capacitor and adapted to measure the voltage impressed upon the capacitor by the energy-converting means upon flashing of a primered mount in said mount holding means.

2. A device for determining the primer bead size of foil-filled flash lamps comprising a double compartmented light-tight chamber, a mount holding bracket in one of the compartments of said chamber, a pair of electrical con tacts on said bracket connected to a source of direct current voltage and adapted to contact the lead wires of a primered mount placed in said bracket, a switch connected between said source of direct current voltage and one of said pair \of electrical contacts, a light-diffusing partition between the compartments of said chamber, a photoelectric cell mounted in the other compartment of said chamber, a source of direct current voltage connected in series with the negative terminal of said photoelectric cell, a capacitor connected in series with the positive terminal of said photoelectric cell, and an electrometer connected in parallel with said capacitor and adapted to measure the voltage impressed upon the capacitor by the photoelectric cell upon flashing of a primered mount in said mount holding bracket.

3. A device for determining the primer bead size of foil-filled flash lamps comprising a double compartrnented light-tight chamber, a mount holding bracket in one of the compartments of said chamber, a pair of electrical contacts on said mount holding bracket connected to a source of direct current voltage and adapted to contact the lead wires of a primered mount placed in said bracket, a switch connected between said source of direct current voltage and one of said pair of electrical contacts, a photoelectric cell in the other compartment of said chamber, an opaque dividing partition between the compartments of said chamber, an orifice in said dividing partition axially aligned between said primered mount and said photocell, a light-difiusing plate over said orifice, a source of direct current voltage connected in series with the negative terminal of said photoelectric cell, a current limiting resistor connected in series with said source of direct current voltage, a capacitor connected in series with the positive terminal of said photoelectric cell, and an electrometer connected in parallel with said capacitor and adapted to measure the voltage impressed upon the capacitor by the photoelectric cell upon flashing of a primered mount in said mount holding bracket.

4. A device for determining the primer head size of foil-filled flash lamps comprising a double compartmented light-tight chamber, a mount holding bracket in one of the compartments of said chamber, a pair of electrical contacts on said mount holding bracket connected to a source of direct current voltage and adapted to contact the lead wires of a primered mount placed in said bracket, a switch connected between said source of direct current voltage and one of said pair of electrical contacts, a photoelectric cell in the other compartment of said chamber, an opaque dividing partition between the compartments of said chamber, an orifice in said dividing partition axially aligned between said primered mount and said photoelectric cell, a light-difiusing plate over said orifice, a source of direct current voltage connected in series with the negative terminal of said photoelectric cell, a current limiting resistor connected in series with said source of direct current voltage, a capacitor connected in series with the positive terminal of said photoelectric cell, a high impedance electrometer connected in parallel with said capacitor and adapted to measure the voltage impressed upon the capacitor by the photoelectric cell upon flashing of a primered mount in said mount holding bracket, and means for shielding the electrometer from the effects of external static electric charges.

References Cited in the file of this patent UNITED STATES PATENTS 2,563,274 Rendel Aug. 7, 1951 2,588,368 Edgerton Mar. 11, 1952 2,765,440 Adelman et a1. Oct. 2, 1956 

